What is Base64 encoding, and how does it function?

A binary-to-text encoding method, Base64 is called. Translating binary data to radix-64 representation, it may be represented in a readable ASCII text format.

Data encoded in Base64 can only cope with the 7-bit US-ASCII charset and is typically used when binary data has to be sent through media that can't handle it properly.

E-mail (SMTP), which uses the 7-bit US-ASCII character set, is a classic example of this kind of technology. For backward compatibility, it is still suggested to encode the data in the ASCII charset, despite the fact that it has since been able to accommodate non-ASCII text messages and non-text communications like audio and graphics.

It encodes binary data or non-ASCII text data into readable ASCII format so that it may be communicated over any communication channel without risk of error. Sending a picture by email, for example, will Base64 encode the image and put it as the following text into your message:

Base64 encoding is explained here.

Base64 encoding is limited to the US-ASCII charset's first 65 characters. An analogous 6-bit binary sequence is mapped to the first 64 characters of the 65-character subset (26 = 64). Padding is provided by the 65th character (=).

From 0-63, the Base64 alphabet is allocated for each 6-bit binary sequence. During the encoding process, a mapping is employed to translate the 6-bit binary sequence into the Base64 alphabet. It's called the Base64 index or alphabet table, and it's below.

Alphabetical representation of the Base64 code

Encoding of Values Coding for Numeric Values Encoding the value Encoding the value
0 A 17 R 34 I 51 z 1 B 18 S 35 j 52 0 2 C 19 T 36 k 53 1 3 D In this case, it is 20 U 37 2 4 E 21 volts, 38 millimetres, and a temperature of 55 degrees Fahrenheit There are 22 ways to solve this problem: G 23 W 39 N 56 4 G 23 X 40 O 57 5 I 25 Z 42 Q 59 7 9 J 26 A 43 R 60 8 10 K 27 B 44 S 61 9 11 L 28 C 45 T +12 M Thirty-nine percent (N) of the population of the United States (N) is made up of 29 percent of the population of the United Kingdom (U.K.). The time now is 03:50:y
An 8-bit byte stream is sent into the Base64 encoding method. It arranges the input into 24-bit groups by concatenating three 8-bit bytes and processes it from left to right. Groups of 24 bits are broken down into four 6-bit concatenated groups. In the end, each 6-bit group is transformed to a single letter in the Base64 alphabet using the above Base64 alphabet table

Adding zero bits (on the right) to produce an integral number of 6-bit groups is used when the input has less than 24 bits remaining. Pad (=) characters are then output depending on the following scenarios: -

Finally, there are 8 bits in the final portion of data: There are now two 6-bit groups after the addition of four zero bits. The Base64 index table is used to turn each 6-bit group into a Base64 encoded character. After that, the output is padded with two equals signs (=).

There are precisely 16 bits in the final segment of input. Three 6-bit groups are formed by adding two zero bits. In order to use the Base64 alphabet, each of the three sets of six bits must be transformed first. Finally, the output is padded with a single equals sign (=).

Let's have a look at an example of Base64 encoding:

input: ab@yz

The 8-bit sequences are represented in binary.

One hundred thousand, one hundred thousand, one hundred thousand, one hundred thousand
Organize the input into groups of 24 bits as the first step (having four 6-bit groups each). Form an integral number of 6-bit groups by padding the end with zero bits.

The number is: 011000 010110 001001 000000 (padded with two zeros at the end)
Step 2: Index the 6-bit sequences into the Base64 index table in order to convert them to Base64 alphabets. Pad character is inserted if there are no more bits in the input.

The following indices correspond to the aforementioned 6-bit groups:

A total of 30 23 40 0 24 22 9
Following an index into the Base64 alphabet table yields the following results:

# (padded with '=' to account for more bits) YWJAeXo=
The use of URL and filename safe alphabets in Base64 encoding.
A Base64 encoding version that is URL and Filename Safe is described in RFC 4648. This implies that URLs and filenames may be securely communicated using the output of this Base64 encoding variant.

The Base64 alphabet has been tweaked in this version. It is because + and / characters in URLs and filenames have a special meaning that they are replaced with a hyphen (-) and underscore character ( ).

# Base 64 Alphabet for "URL and Filename Safe"

Encoding the value of a certain item One of the values encoded is zero, while the other values are zero, one, and three. In this case, it is 20 U 37 2 4 E 21 volts, 38 millimeters, and a temperature of 55 degrees Fahrenheit 26 A 43 R 60 8 10 K 27 B 44 S 61 9 11 L 28 C 45 t (hyphen)
It was 12:29 a.m. on the 29th day of the month (underscore)
To calculate the answer, use the following formula: 13 N 30 E 47 V 14 O 31 F 48 W (pad) = 15 P 32 G 49

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